Almost 50 inches of rain fall in the United States annually. That adds up to around 3 trillion gallons of water falling over our heads every year. Assuming the average person uses around 100 gallons a day, 50 inches of rainfall a year can provide enough water for almost 30 million people. Unfortunately, only a small fraction of rainwater is harvested and put to good use.
Water Harvesting is the collection and storage of rainwater and storm water runoff in order to provide water for livestock, irrigation, drinking, recharging of groundwater, and other purposes. This collection of rainwater/storm water also has the added benefit of reducing erosion and flooding that may result from heavy rains.
There are two general categories of water harvesting: rainwater harvesting and storm water harvesting. Rainwater harvesting, as the name implies, involves catching rainwater where it falls – usually on rooftops and other small catchments. Stormwater harvesting captures from ground catchments, storm drains, and even streams, rivers, or other bodies of water – this makes storm water harvesting suitable for collecting large amounts of water from wide areas.
Harvested water can be used for different purposes, including replenishment of groundwater, irrigation of plants and crops, cleaning purposes such as washing clothes and flushing toilets, and even drinking water. This means that the harvested water usually goes through filtering and treatment before being put back to re-use.
Initial pre-treatment usually involves a mesh or some other filter to block large objects in the water such as twigs, leaves, insects, and others. From here, the water goes through finer filters such as a sand and gravel filter to clean it further. At this point, the water is suitable for an aquifer or deep well, recharging the groundwater. This water can also be used for many household purposes, such as: for watering plants/crops, for use as supply of water for toilets, and outdoor wash-bays. With further sanitization and sterilization, the water can also be re-used for: personal bathing and for washing dishes.
Though this water may already be potable, it usually goes through further treatment to ensure that there are no impurities and contaminants in the water. Adding chlorine, exposing the water to UV light, and passing it through very fine filters are just some measures taken to sterilize harvested water.
This is just a brief look at water harvesting and the steps involved in maximizing the use of captured rain and stormwater. To learn more, visit Landtech Irrigation Consultants at http://www.LandtechDesign.com/ and stay tuned for more posts here.